This article investigates the relationship between socialisation and the concept of linguistic muda in a community of practice that belongs to a social movement called Emmaus. Based on a long-term ethnography (2008–2017), the article focuses on two transnational migrants who undergo a linguistic muda into functionally bilingual Catalan through participation in communal activities at Emmaus Barcelona. The analysis firstly traces the tensions arising in linguistic negotiation during a migrant novice’s initial participation in assemblies as a “socialising routine”. Although established participants of all origins projected a preferred bilingual stance and routinely code-switched, newly-arrived migrants were initially addressed in Spanish, in line with the commonsensical sociolinguistic behaviour routinely adopted with migrants in Catalonia. Analysis of the two migrants’ socialisation trajectories in Emmaus illuminates the changing sociolinguistic norms in Catalonia that legitimise transnational migrants’ linguistic mudes in this community. In conclusion, acceptance as a legitimate speaker of Catalan at Emmaus Barcelona can be viewed as a means to an end: that of becoming a legitimate member, capable of participating in joint (inter)
actions such as assemblies.